The two composed questions are:
Describe the four major classifications of clouds and identify their distinctions.
Explain what atmospheric stability and instability imply.
How Does Water Circulate the Earth and Atmosphere?
The circulation of water between the earth surface and atmosphere is known as the hydrological cycle. Before analyzing this cycle, it is worth revisiting the forms and places in which water exist. Glaciers, lakes, rivers, and vapor in the air, are some of the places in which water exists. Because the ocean occupies about 70% of the earth surface, the hydrological cycle is thought to be initiated from it ( Raudkivi, 2013). However, in this process, the solar energy is so fundamental since the transformation of water into three distinct forms depends on the energy applied. Evaporation, condensation, and precipitation are the three major processes that well explain the transformation of water from one form to the other (p.80).
The evaporation process is where liquid water in the ocean, rivers or lakes is transformed into vapor. The solar energy raises the temperature of liquid water thus causing the molecules to collide more. If the molecules on the water surface accumulate more energy than the vapor pressure, they are automatically converted to a gaseous form. It is also important to note that this process only stops when both the condensation and vaporization processes reach an equilibrium. After the liquid water has been converted into a gaseous form, wind transports the moist air to other cooler regions where the condensation process is initiated.
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Once the moist air is in the atmosphere, particles of dust and other gaseous molecules act as the condensation nuclei. If the vapor is warm, the molecules will strike the nuclear but will not get attached to it due to their high speed. Therefore, for the condensation process to take place, the moist air must be chilled for the moisture particles to stick on the nuclei. Millions of such water droplets in the sky saturate the atmosphere thus limiting the rate of vaporization. Condensation can occur both at a ground level or in the atmosphere depending on where the dew point is achieved. Even though condensation thrives in cool environments, warm air can hold more water vapor molecules before saturation is reached ( Jones, 2014) . With this postulation, it is prudent to concur with the fact that warm air holds huge amounts of water vapor as compared to cold air (p.82). The main reason behind this assertion is that warm air takes longer to reach its saturation limits. At a ground level, condensed water is called mist or fog. Air pressure is also a factor that influences the saturation limit in this process.
The water in the atmosphere is then directed towards the earth surface through precipitation. Unlike condensation and evaporation, precipitation is not complex since it only describes the process in which water falls from the sky in the form of rain, hail, and snow. However, it is also worth contextualizing the fact that fog is not precipitation. This is because fog does not liquefy and fall on the earth surface. With this assertion, it is very clear that precipitation is among the three major ways in which water circulates between the atmosphere and the earth surface. However, it is worth noting that the evaporation, condensation, and precipitation are not the only processes in the hydrological cycle. For instance, transpiration is an important process in the hydrological cycle. This process involves the release of water vapor from plants to the atmosphere through their microscopic pores. In connection with the evaporation processes, the term evapotranspiration has been used to describe the general vaporization of water to the atmosphere.
What is the Process of Cloud Seeding and Why is it so Controversial?
The answer to his question can be obtained in Essentials of Meteorology by Ahrens from page 129 to 130. Cloud seeding is a weather modification process that entails injecting condensation nuclei in the atmosphere. The main motive behind this process is to increase the intensity of precipitation. However, in some areas where fog and hail are common, cloud seeding technique can be used to suppress the adverse weather conditions. Silver iodide, dry ice, and potassium iodide are some of the chemicals used in this process. Also, several scholars have postulated that table salt is very efficient for cloud seeding (Griffin, 2018). Because snowfall is prominent when the cloud temperature is between -20 and -7 degrees Celsius, any introduction of chemicals such as silver iodide induces freezing nucleation (Griffin, 2018). However, in situations where the air temperature is not at the freezing point, the upper part of the cloud is subjected to a supercooling process (p. 129). The main motive in this process is to identify some of the clouds that exhibit low droplets to ice crystal ratio to induce additional nuclei.
Even though the cloud seeding process is varied depending on the type of chemical used, it is worth analyzing the original experiment carried out by Vincent and Irving in 1940s (p.129). For the success of a seeding process, a cloud must be present. Therefore, the process is initiated by having a plane drop pellets of dry ice or any other chemical in the identified cloud. Going by the Vincent and Irving experiment, dry ice is used because it acts as a cooling agent. It has a temperature of about -78 degrees Celsius which makes it a superior cooling agent. The main role of dry ice pellets, in this case, is to cool the moist air to supersaturation. Therefore, the water vapor surrounding the ice pellets is transformed into numerous tiny cloud droplets in the atmosphere. As the air temperatures fall further below -40 degrees Celsius, the formed droplets of water freeze into tiny ice crystals which then grow into large portions of ice deposits (p.129). Therefore, the fully-grown ice crystals in the atmosphere act as nuclei in which water droplets get attached, and upon reaching some sufficient sizes, they fall as precipitation.
Even though dry ice seemed effective, Bernard Vonnegut demonstrated that indeed silver iodide could also be used in cloud seeding (Griffin, 2018). The only difference with dry ice is that silver iodide causes crystal nuclei to form in the following two major ways. In one way, the supercooled water droplets are converted into crystal form when they come in contact with the cold silver iodide crystals. Secondly, the crystals of ice grow in size as supercooled water gets in contact with silver iodide pellets. In comparison to other chemicals, silver iodide is the most commonly used because it is easy to handle.
However, the cloud seeding process is regarded as being controversial since it surpasses the law of nature. More so cloud seeding can also occur under natural condition by having one cloud rest above the other. Therefore, as the ice crystals of the top cloud are injected into the lower one, the supercooled water droplets of the lower cloud initiate the formation of nuclei. Cloud seeding is also considered a controversial process because of the climatic effects associated with it. For instance, China used cloud seeding technique in the year 2009 to end the drought, but it led to a drop in temperatures in the region (Bodle, 2013). Furthermore, the resurgence of business companies such as Atmospheric Inc has made cloud seeding a controversial issue. With the profits held key, these companies are likely to plunge the world into health issues associated with silver iodide toxins. For instance, in 2006, the cloud seeding project caused deaths and damage to property in China. Also, in the UN convention of 1977, cloud seeding was pinpointed as a way to precipitate international conflicts (Zilinskas, 2017).
References
Ahrens, C. D. (2018). Essentials of meteorology: an invitation to the atmosphere . Cengage Learning.
Bodle, R. (2013). Climate law and geoengineering. In Climate change and the law (pp. 447-470). Springer, Dordrecht.
Griffin, E. (2018). “Science is Magic that works”: science and technology in the early Work of Kurt Vonnegut, 1952-1963.
Jones, J. A. A. (2014). Global hydrology: processes, resources and environmental management . Routledge.
Raudkivi, A. J. (2013). Hydrology: An advanced introduction to hydrological processes and modeling . Elsevier.
Zilinskas, R. A. (2017). Preventing state crimes against the environment during military operations: The 1977 Environmental Modification Treaty. In Controlling State Crime (pp. 235-281). Routledge.
